On Tue, Feb 25, 2014 at 1:39 AM, Alex Bennée alex.bennee@linaro.org wrote:
Dann Frazier dann.frazier@canonical.com writes:
On Mon, Feb 17, 2014 at 6:40 AM, Alex Bennée alex.bennee@linaro.org wrote:
Hi,
Thanks to all involved for your work here!
After a solid few months of work the QEMU master branch [1] has now reached instruction feature parity with the suse-1.6 [6] tree that a lot of people have been using to build various aarch64 binaries. In addition to the
<snip> >> >> I've tested against the following aarch64 rootfs: >> * SUSE [2] >> * Debian [3] >> * Ubuntu Saucy [4] > > fyi, I've been doing my testing with Ubuntu Trusty.
Good stuff, I shall see if I can set one up. Is the package coverage between trusty and saucy much different? I noticed for example I couldn't find zile and various build-deps for llvm.
<snip> >> >> Feedback I'm interested in >> ========================== >> >> * Any instruction failure (please include the log line with the >> unsupported message) >> * Any aarch64 specific failures (i.e. not generic QEMU threading flakeiness). > > I'm not sure if this qualifies as generic QEMU threading flakiness or not. I've > found a couple conditions that causes master to core dump fairly > reliably, while the aarch64-1.6 branch seems to consistently work > fine. > > 1) dh_fixperms is a script that commonly runs at the end of a package build. > Its basically doing a `find | xargs chmod`. > 2) debootstrap --second-stage > This is used to configure an arm64 chroot that was built using > debootstrap on a non-native host. It is basically invoking a bunch of > shell scripts (postinst, etc). When it blows up, the stack consistently > looks like this:
I've narrowed down the changes that seem to prevent both types of segfaults to the following changes that introduce a wrapper around sigprocmask:
https://github.com/susematz/qemu/commit/f1542ae9fe10d5a241fc2624ecaef5f0948e... https://github.com/susematz/qemu/commit/4e5e1607758841c760cda4652b0ee7a6bc6e... https://github.com/susematz/qemu/commit/63eb8d3ea58f58d5857153b0c632def1bbd0...
I'm not sure if this is a real fix or just papering over my issue - but either way, are these changes reasonable for upstream submission?
-dann
Core was generated by `/usr/bin/qemu-aarch64-static /bin/sh -e /debootstrap/debootstrap --second-stage'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x0000000060058e55 in memcpy (__len=8, __src=0x7fff62ae34e0, __dest=0x400082c330) at /usr/include/x86_64-linux-gnu/bits/string3.h:51 51 return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest)); (gdb) bt #0 0x0000000060058e55 in memcpy (__len=8, __src=0x7fff62ae34e0, __dest=0x400082c330) at /usr/include/x86_64-linux-gnu/bits/string3.h:51 #1 stq_p (v=274886476624, ptr=0x400082c330) at /mnt/qemu.upstream/include/qemu/bswap.h:280 #2 stq_le_p (v=274886476624, ptr=0x400082c330) at /mnt/qemu.upstream/include/qemu/bswap.h:315 #3 target_setup_sigframe (set=0x7fff62ae3530, env=0x62d9c678, sf=0x400082b0d0) at /mnt/qemu.upstream/linux-user/signal.c:1167 #4 target_setup_frame (usig=usig@entry=17, ka=ka@entry=0x604ec1e0 <sigact_table+512>, info=info@entry=0x0, set=set@entry=0x7fff62ae3530, env=env@entry=0x62d9c678) at /mnt/qemu.upstream/linux-user/signal.c:1286 #5 0x0000000060059f46 in setup_frame (env=0x62d9c678, set=0x7fff62ae3530, ka=0x604ec1e0 <sigact_table+512>, sig=17) at /mnt/qemu.upstream/linux-user/signal.c:1322 #6 process_pending_signals (cpu_env=cpu_env@entry=0x62d9c678) at /mnt/qemu.upstream/linux-user/signal.c:5747 #7 0x0000000060056e60 in cpu_loop (env=env@entry=0x62d9c678) at /mnt/qemu.upstream/linux-user/main.c:1082 #8 0x0000000060005079 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at /mnt/qemu.upstream/linux-user/main.c:4374
There are some pretty large differences between these trees with respect to signal syscalls - is that the likely culprit?
Quite likely. We explicitly concentrated on the arch64 specific instruction emulation leaving more generic patches to flow in from SUSE as they matured.
I guess it's time to go through the remaining patches and see what's up-streamable.
Alex/Michael,
Are any of these patches in flight now?
Cheers,
-- Alex Bennée QEMU/KVM Hacker for Linaro